Before I start, NO PICTURES ON THIS FIRST POST ARE MY OWN - they are from the net for reference only. I`ve been collecting pictures for years - if I can reference, I will do. I am posting for inspiration and ideas.

For many years I have wanted a clock wheel depthing tool. This tool allows you to correctly distance a wheel and pinion and then scribe the correct distance onto the frame.

This is commercial clock depthing tool:

The runners sticking out of the end are then used to scribe a line to correct depth by turning the device vertical:

A cheap simple depthing tool can be made by plans described in several books I own, specifically by John Wilding and Colin Thorne. This is good for the majority of jobs, but at 30 years old, I`d like to keep this for a good time and would like to invest more time in to making a more traditional and more versatile tool.From Dean and Deans Photographica:

There are loads and loads of homebrew depthing tools on the internet. My issue is that they rarely describe the machining process to ensure they maintain parallelism between the two split runners. Also, I`m not clear how the hinge is made or designed to ensure the two parts are held firmly without wobble but lose enough to be moved. I also don`t know how the spring is being applied to force the two halves together!!

Taking madmodding to the limits, here is a Perspex tool with elastic band as the spring. Made by John Prevatte:

And another, this one made from a door hinge by Jay Fortner:

This homemade design, unfortunately I don`t know the maker, has a slightly different clamp down top, rather than the V groove style holder for the runners:

Aluminium body, again I don`t know the maker but has a more homemade feel about it - no idea how it being sprung

This is smart spring method - I can clearly see how this is working but would you need to have a spring on each side to ensure even pressure is put on both sides otherswise the frame could twist, depending on the rigidy of the hinge:

Lots of food for thought! If you have any ideas or suggestions as to how to make one, I`d appreciate your input. The key is getting the runners parallel and a solid hinge between the two parts but allowing you to fine adjust the two.

I believe there is a full article: MEW no 8 Dec 91 jan 92 - if anyone has a copy of this article, I`d be really grateful!

Just from my dumb stand back and imagine basic process approach to stuff like this, I see:

1.) The hinge is the hardest part to make, and most important part -- everything else follows. So make the hinge first, as precisely as you can, ignoring the rest of the needs. Make the hinge whatever way or shape you want. But just get that part fabricated.

2.) Then fasten or clamp the hinged assembly to a mill or boring table. You can now drill/bore arbor holes/bearings whatever. If you index the table without loosening the part, you will automatically make holes parallel to each other and the established hinge line. (Assuming you clamped it true to that line, in the first place, of course).

ps. a boring table on the lathe might be better for this than a vertical mill -- depends on the size of the piece.

Thanks for the info so far. If a bar running in v grooves is used for the hinge, I dont see how the assembly is held together, I.e force at the bottom on the bar.

That would be more Vert-Mill friendly than long bored holes. I tend to still think boring because that's how my homemade lathe came together, long before I had a vertical mill. But V-grooving everything makes a lot of sense. You can do all the main body grooves without shifting the part in the clamping setup, which makes them all parallel. Good way to do it!

BillTodd - I really really like the ball bearing suggestion! I know I'm being thick but I'm still not clear how they would be held and forced together. Obviously some have the obvious spring on the side bar I mentioned in my first post but I can't see how the others are spring closed without this. I understand the adjuster is putting pressure on the hinge, bar, ball bearings but what is holding them from just falling apart. Bill - also, why 4 bearings in each top corner?

This method would stop me needing to machine a parallel v groove for the bar hinge, I'd still need to machine, either mill a groove or bore a long parallel hole along each top side for the runners right.

The length of the depthing tool will be about 170mm long... That's a long way to bore two holes!!

Perhaps using a flexure instead of a hinge would do the job. Mill grooves in the bottom of the two uprights and solder or epoxy in a strip of springy steel -- a bit of metal strapping might do the job. Mill a pair of grooves into a base plate and solder or epoxy the other side of the strips into it. You will have a fairly limited range of travel but it would probably be adequate for your needs.

If you really want to be fancy, for the adjusting screws you could make a differential screw from a 4mm coarse and a 6mm fine capscrew. Machine the head off of the 4mm and remove a cm or so of threads and drill a hole of an appropriate diameter and depth into the 6mm fastener. Press fit, loctite or solder the 4 mm bit into the 6mm. Put a post drilled and tapped with a 4mm coarse thread on one arm and one with a 6mm fine thread on the other. That would give you an effective screw pitch of .05 mm per turn. At least one of your posts would have to be removable for coarse adjustment. Might be overkill.

BillTodd, have you by any chance dimensional drawings for that? It looks very much in proportion and would give me a scale to work from. The next question is brass, steel or aluminium? - brass looks the part but is pricy.

I wonder now if it would be nicer if the depth adjusting screw was now placed more centrally, in the position of the old spring hole perhaps.

Also, I'm just wondering if it would be better to slightly oversize the holes in the runner threaded rods. My thoughts were getting onto reaming these accurate but actually, there job is only to pull the runners against the bearings so having the hole larger would I expect be better, allowing the runner to find its true seat.

Also,could the balls be soldered in position or is this likely to push them out of position slightly with the solder running below them. I would have thought that there wouldn't be a right lot for the glue to stick to.

BillTodd, have you by any chance dimensional drawings for that? It looks very much in proportion and would give me a scale to work from.

I can make it any size you want ATM it's plates are 100mm wide, throat 80mm x 40 ish The spring clip is 50mm long

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The next question is brass, steel or aluminium? - brass looks the part but is pricy.

Aluminium might be a bit soft (you don't want the balls digging in too much) Stainless (say 3-4mm think) would be good Brass 3/16" - 1/4" would be fancy (and should always be quoted in imperial units! LOL)

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I wonder now if it would be nicer if the depth adjusting screw was now placed more centrally, in the position of the old spring hole perhaps.

Yes. it needs a a rotating/hinging mechanism (left & right thread with thumb wheel in the middle?)

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Also, I'm just wondering if it would be better to slightly oversize the holes in the runner threaded rods. My thoughts were getting onto reaming these accurate but actually, there job is only to pull the runners against the bearings so having the hole larger would I expect be better, allowing the runner to find its true seat.

Absolutely right I need to check that the guide ball spacing is OK and that it wont just ping the balls out when tightened

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Also,could the balls be soldered in position...

Why not. Clamp and solder from the hole side should keep any lifting to a minimum.

I have purchased the brass needed for the depthing tool today - 1/4". Would two large bulldog clips be more suitable?

Could you just explain your thoughts on bearing size for the pivot/hinge? You mentioned 4.5mm in a 4mm reamed hole. You also mentioned that slightly larger may be better for the hinge - why? And what size - 5mm, 6mm?

I'm guessing I'd need to keep 1.25" of meat at the bottom to give room from the spring clip and adjuster. That'll leave 1.75" to centre allowing a 3.5" maximum dia wheel. That would be a substantial wheel. Length wise, at 175mm - that's just short of 8" - having 1.5" sides also would give a distance of 5", about 100mm maximum distance between runners I.e max pivot size. Any thoughts?

So why can't the hinge part of this just be a piano hinge all it does is open up.? The acuracy to me would be in the shaft suports and if there is enough room to drill and ream for the spring tension in the shaft to hold the gears.

So why can't the hinge part of this just be a piano hinge all it does is open up.? The acuracy to me would be in the shaft suports and if there is enough room to drill and ream for the spring tension in the shaft to hold the gears.

It can be any kind of hinge as long as it is parallel to the axles - it is ensuring the alignment of all the parts that is critical.

Yes, the bigger the hinge balls the larger the opening (although this also requires a bigger diameter spring)

ATM I am experimenting with a 15mm ball. This gives it a 66mm axle spacing (not much point in holding one large gear only)

I've been looking around at bull dog clips the largest standard type clip (70mm wide) has a maximum throat of 17mm (the spring would probably open to 20+), which is a bit too small even with small ball hinges.

The commercial Webster design gives a maximum 3 3/4" swing between axel centres but this is generally bigger overall than this one. I appreciate practically it'll work but aesthetically odd! Also, it may be tricky holding smaller wheels if placed on the outside.

Bill - what opening does that give? Thinking about it, the opening would have to be larger than the maximum wheel diameter radius. Otherwise, the depth would allow you to fit the wheel on but if you couldnt space it to the radius, you could not mesh it with a pinion.

Hmmmm, felt like I kind of stalled the discussion. Too bad and not my meaning. To try to illustrate what I was after, I quickly made a 2D sketch.It is based not on a ruler but on two bars, say about 6 mm dia and some various sized brass blocks about 25 mm high and 10 mm thick. Should be sturdy enough. Thickness probably OK if 8 mm.

The two end pieces are pinned to limit the risk for twisting. At the right end the end block is wider and carries one of the depthing pegs. The other larger block slides sweetly on the bars without any slop at all. This block carries the other depthing peg.

To achieve a micrometer adjustment, the smaller moving block to the left of the left peg block, has a locked in thumb screw working into a thread in the adjacent peg block. With a spring between them it will be easy to adjust minutely the gear centres.

Locking the depthing pegs is done like a height gauge and locking the peg block and adjustment block is done using a cross "bar" nipping the slide rods like the arm locks on a GHT pillar tool.

This would be easy to make and if the rod holes are drilled and reamed before parting the brass bit, the distances will be exact. Probably simple to make as well.

I thought that the depthing pegs shall allow to insert a 2mm? gear axle at the top to fit the gears on, and then when marking exchange the 2mm pins for a piece of say 5/2 mm extension piece to tap upon.

Much like the image on page 1 of this thread where the depthing pegs goes bweteen the "bars" 90 degrees compared with my sketch.

I thought that the depthing pegs shall allow to insert a 2mm? gear axle at the top to fit the gears on, and then when marking exchange the 2mm pins for a piece of say 5/2 mm extension piece to tap upon.

Much like the image on page 1 of this thread where the depthing pegs goes bweteen the "bars" 90 degrees compared with my sketch.

Hi guys and hi Bill, I know you have been putting a lot of effort into helping me here. I'm actually moving - it's all happened unbelievably quick and although we still have a good number of weeks until move day, getting the workshop in storage was priority as everything is so heavy and I happened to have some storage offered to me! I genuinely went and purchased that 1/4" brass and then the next day turned the power off to my machines and now they are gone!

I can assure you, this will be the first project on the list when I get going again.....whenever this may be!

In the mean time I keen to get a plan in place and continue with the discussion!

Although I have nothing to do with clock making, this thread is of great interest and value. I am enjoying the development process! I wish I had a use for a Gear Depth Tool, it looks like a satisfying build.

OK, some sketching later. To begin, I did some more thinking about the micrometer adjustment screw and changed the design as shown at B in the sketch below.This way I can use an ordinary thumb screw and keep it tight using a spring between the thumb screw runner and the depthing peg runner.

When it comes to locking the runners to the bars I would use the same type of lock as I used on the bed stop for my lathe.The distance setting pin is locked using an intersecting "bolt" secured with a thumb nut. The works is shown below.I think it is easy to see which is the locking "bolt" in the picture.

I think this type of lock is good. Easy to handle and locks with strength.

Bill, I'm not going to lie. Since having this discussion I have actually got my hands on some original Malcolm Wild depthing tool castings. However, I promise you I'm so excited about the ball bearing idea that I'm going to attempt making that as my first project when my workshop is setup!!

The day after I purchased all the metal and even the ball bearings, I sold my house and in panic packed up my workshop. I've only just got the new shop straight and ready for action. This is still on my immediate to do list, in fact, I genuinely got the material out a few weeks back. I'll Certainly be reading the article if I can get my hands on a copy... if I can get my hands on a copy if I can get my hands on a copy

Well its been months since I last posted and I`ve been moving forward at a snail pace. Anyway, finally its been made.

It may have been 3 years ago or more, but the concept works and the project is finally finished.

Thanks to everyone who chipped in on here and especially Bill Todd for all his drawings and thoughts. Appreciate the video may not be to everyone's taste but I enjoy putting them together and each to their own. Certainly shows the build and final product! I`m always looking for constructive criticism and opinions as to my machining! Cheers

At the end of the video i was thinking you will have to get the measurement from the centers of the pins i was so surprised to see it doubles as a divider a very clever design... you made a smashing job of your tool.